[PATCH 7/7] fsck: complain when .gitattributes or .gitignore is a symlink

[Jeff King <peff@peff.net>]

The previous commit made it impossible to have a symlinked
.gitattributes or .gitignore file via verify_path(). Let's add the same
check to fsck, which matches how we handle .gitmodules symlinks, via
b7b1fca175 (fsck: complain when .gitmodules is a symlink, 2018-05-04).

Note that we won't add these to the existing gitmodules block. Its logic
is a bit more complicated, as we also check the content of non-symlink
instances we find. But for these new files, there is no content check;
we're just looking at the name and mode of the tree entry (and we can
avoid even the complicated name checks in the common case that the mode
doesn't indicate a symlink).

Signed-off-by: Jeff King <peff@peff.net>
---
 fsck.c                    | 15 +++++++++++++++
 t/t7450-bad-meta-files.sh |  9 +++++++++
 2 files changed, 24 insertions(+)

diff --git a/fsck.c b/fsck.c
index 024810139b..fcd3f268b1 100644
--- a/fsck.c
+++ b/fsck.c
@@ -67,6 +67,8 @@ static struct oidset gitmodules_done = OIDSET_INIT;
 	FUNC(GITMODULES_URL, ERROR) \
 	FUNC(GITMODULES_PATH, ERROR) \
 	FUNC(GITMODULES_UPDATE, ERROR) \
+	FUNC(GITIGNORE_SYMLINK, ERROR) \
+	FUNC(GITATTRIBUTES_SYMLINK, ERROR) \
 	/* warnings */ \
 	FUNC(BAD_FILEMODE, WARN) \
 	FUNC(EMPTY_NAME, WARN) \
@@ -688,6 +690,19 @@ static int fsck_tree(const struct object_id *tree_oid,
 						 ".gitmodules is a symbolic link");
 		}
 
+		if (S_ISLNK(mode)) {
+			if (is_hfs_dotgitignore(name) ||
+			    is_ntfs_dotgitignore(name))
+				retval += report(options, tree_oid, OBJ_TREE,
+						 FSCK_MSG_GITIGNORE_SYMLINK,
+						 ".gitignore is a symlink");
+			if (is_hfs_dotgitattributes(name) ||
+			    is_ntfs_dotgitattributes(name))
+				retval += report(options, tree_oid, OBJ_TREE,
+						 FSCK_MSG_GITATTRIBUTES_SYMLINK,
+						 ".gitattributes is a symlink");
+		}
+
 		if ((backslash = strchr(name, '\\'))) {
 			while (backslash) {
 				backslash++;
diff --git a/t/t7450-bad-meta-files.sh b/t/t7450-bad-meta-files.sh
index 6a038ed55b..c7201803ec 100755
--- a/t/t7450-bad-meta-files.sh
+++ b/t/t7450-bad-meta-files.sh
@@ -281,6 +281,11 @@ test_expect_success 'refuse to load symlinked .gitattributes into index' '
 	test_i18ngrep "invalid path.*gitattributes" err
 '
 
+test_expect_success 'fsck detects symlinked .gitattributes file' '
+	test_must_fail git -C symlink-attr fsck 2>err &&
+	test_i18ngrep "tree $tree: gitattributesSymlink" err
+'
+
 test_expect_success 'create repo with symlinked .gitignore file' '
 	git init symlink-ignore &&
 	target=$(echo target | git -C symlink-ignore hash-object -w --stdin) &&
@@ -295,5 +300,9 @@ test_expect_success 'refuse to load symlinked .gitignore into index' '
 	test_i18ngrep "invalid path.*gitignore" err
 '
 
+test_expect_success 'fsck detects symlinked .gitignore file' '
+	test_must_fail git -C symlink-ignore fsck 2>err &&
+	test_i18ngrep "tree $tree: gitignoreSymlink" err
+'
 
 test_done
-- 
2.28.0.1295.g4824feede7